The Spanish vendimia (“a harvest of wine”) comes from the Latin vinum (“wine” — from which we get words like vino — “wine” — in Spanish) combined with demere, which meant, “to take out”. So the wine harvest is literally, the taking out of the wine.
The interesting part is that, from these same two roots, we get the English… vintage. You may think of vintage cars or vintage clothing — but it really does just refer to taking out wine.
We can see the v-n-d of vendimia maps to the v-n-t of vintage.